Condensed Consolidating Financial Information - Statements of Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Condensed Consolidating Financial Information
Revenue	$ 1,609	$ 1,577
Costs and Expenses:
Cost of Revenue	614	629
Depreciation and Amortization	184	194
Selling, General and Administrative	547	599
Total Costs and Expenses	1,345	1,422
Operating Income (Loss)	264	155
Other Income (Expense):
Interest income		0
Interest expense	(151)	(169)
Interest income (expense) affiliates, net	0	0
Equity in net earnings (losses) of subsidiaries	0	0
Other, net	6	(50)
Total Other Expense	(145)	(219)
Income (Loss) before Income Taxes	119	(64)
Income Tax Expense	(7)	(14)
Net Income (Loss)	112	(78)
Other Comprehensive Income (Loss), Net of Income Taxes	6	(52)
Comprehensive Income (Loss)	118	(130)
Level 3 Communications, Inc.
Condensed Consolidating Financial Information
Revenue	0	0
Costs and Expenses:
Cost of Revenue	0	0
Depreciation and Amortization	0	0
Selling, General and Administrative	0	1
Total Costs and Expenses	0	1
Operating Income (Loss)	0	(1)
Other Income (Expense):
Interest income
Interest expense	(34)	(39)
Interest income (expense) affiliates, net	288	273
Equity in net earnings (losses) of subsidiaries	(142)	(311)
Other, net		0
Total Other Expense	112	(77)
Income (Loss) before Income Taxes	112	(78)
Income Tax Expense	0	0
Net Income (Loss)	112	(78)
Other Comprehensive Income (Loss), Net of Income Taxes	6	(52)
Comprehensive Income (Loss)	118	(130)
Level 3 Financing, Inc.
Condensed Consolidating Financial Information
Revenue	0	0
Costs and Expenses:
Cost of Revenue	0	0
Depreciation and Amortization	0	0
Selling, General and Administrative	0	0
Total Costs and Expenses	0	0
Operating Income (Loss)	0	0
Other Income (Expense):
Interest income
Interest expense	(112)	(126)
Interest income (expense) affiliates, net	459	430
Equity in net earnings (losses) of subsidiaries	(488)	(614)
Other, net		(1)
Total Other Expense	(141)	(311)
Income (Loss) before Income Taxes	(141)	(311)
Income Tax Expense	(1)	0
Net Income (Loss)	(142)	(311)
Other Comprehensive Income (Loss), Net of Income Taxes	0	(52)
Comprehensive Income (Loss)	(142)	(363)
Level 3 Communications, LLC
Condensed Consolidating Financial Information
Revenue	737	685
Costs and Expenses:
Cost of Revenue	290	261
Depreciation and Amortization	70	71
Selling, General and Administrative	325	381
Total Costs and Expenses	685	713
Operating Income (Loss)	52	(28)
Other Income (Expense):
Interest income
Interest expense	(1)	(1)
Interest income (expense) affiliates, net	(712)	(669)
Equity in net earnings (losses) of subsidiaries	178	146
Other, net	3	1
Total Other Expense	(532)	(523)
Income (Loss) before Income Taxes	(480)	(551)
Income Tax Expense	(1)	(1)
Net Income (Loss)	(481)	(552)
Other Comprehensive Income (Loss), Net of Income Taxes	0	0
Comprehensive Income (Loss)	(481)	(552)
Other Non-Guarantor Subsidiaries
Condensed Consolidating Financial Information
Revenue	931	956
Costs and Expenses:
Cost of Revenue	383	432
Depreciation and Amortization	114	123
Selling, General and Administrative	222	217
Total Costs and Expenses	719	772
Operating Income (Loss)	212	184
Other Income (Expense):
Interest income
Interest expense	(4)	(3)
Interest income (expense) affiliates, net	(35)	(34)
Equity in net earnings (losses) of subsidiaries	0	0
Other, net	3	(50)
Total Other Expense	(36)	(87)
Income (Loss) before Income Taxes	176	97
Income Tax Expense	(5)	(13)
Net Income (Loss)	171	84
Other Comprehensive Income (Loss), Net of Income Taxes	6	(52)
Comprehensive Income (Loss)	177	32
Eliminations
Condensed Consolidating Financial Information
Revenue	(59)	(64)
Costs and Expenses:
Cost of Revenue	(59)	(64)
Depreciation and Amortization	0	0
Selling, General and Administrative	0	0
Total Costs and Expenses	(59)	(64)
Operating Income (Loss)	0	0
Other Income (Expense):
Interest income
Interest expense	0	0
Interest income (expense) affiliates, net	0	0
Equity in net earnings (losses) of subsidiaries	452	779
Other, net	0	0
Total Other Expense	452	779
Income (Loss) before Income Taxes	452	779
Income Tax Expense	0	0
Net Income (Loss)	452	779
Other Comprehensive Income (Loss), Net of Income Taxes	(6)	104
Comprehensive Income (Loss)	$ 446	$ 883